Approximately 56,000 new cases of bladder carcinoma are diagnosed each year. Of the newly diagnosed cases, 75-85% are superficial tumors (Ta, T1 and Tis) and 15-25% are invasive tumors (T2-4). The primary treatment for superficial bladder carcinomas is transurethral resection, i.e., surgical removal of the tumor. Unfortunately, tumors recur in 40% to 80% of the patients who undergo transurethral resection. Among the patients with recurrent tumors, 10-20% suffer tumor progression, i.e., muscular invasion or metastasis. Drugs such as methotrexate, doxorubicin, or cisplatin are often administered systemically to patients with invasive or metastatic bladder carcinomas.
Recently, studies have been conducted to determine whether an adjuvant intravesical therapy would be useful for preventing tumor recurrence in patients with superficial bladder carcinomas. Intravesical therapy involves direct administration of a drug into the bladder of the patient following transurethral resection. The goal of adjuvant intravesical therapy is to eliminate the neoplastic and pre-malignant cells that are not removed by surgery.
A few studies have been conducted on the effect of intravesical administration MMC or bacillus Calmette Guerin (BCG). The customary experimental MMC intravesical therapy involved weekly administration of MMC at a dose of 1 mg/ml in 20-40 ml of water for six to eight weeks. These studies have shown that an additional 1-13% of the patients who received the customary experimental MMC intravesical therapy following transurethral resection did not display or have a recurrent tumor at 1 year as compared to patients who undergo transurethral resection alone. Thus, although it was possible to reduce tumor recurrence by the customary experimental MMC intravisical therapy, the improvement was relatively modest.
Accordingly, it is desirable to have a new adjuvant therapy for treating patients with superficial bladder carcinomas.